1. Field of the Invention
This invention relates to a disk drive flexure used for a head gimbal assembly of a disk drive.
2. Description of the Related Art
A hard disk drive (HDD) is used in an information processor such as a personal computer. The HDD comprises a magnetic disk rotatable about a spindle, a carriage turnable about a pivot, etc. On an arm of the carriage, a disk drive suspension (which will be hereinafter simply referred to as a suspension) is provided.
The suspension comprises a load beam, and a flexure disposed to overlap the load beam. A magnetic head including a slider is mounted on a gimbal portion formed near a distal end of the flexure. The magnetic head is provided with elements for accessing data, that is, for reading or writing data. The suspension, the flexure, etc., constitute a head gimbal assembly.
Various types of flexures have been put to practical use according to the required specification. As an example of the flexure, a flexure with conductors is known. The flexure with conductors includes a metal base made of a thin stainless steel plate, an insulating layer made of an electrically insulating material, such as polyimide, which is formed on the metal base, and a plurality of conductors formed on the insulating layer. The flexure includes a portion which overlaps the load beam, and a flexure tail which extends toward the back of a baseplate.
Part of the conductors is for writing, and the other part of the same is for reading. Ends of these conductors are connected to elements (for example, MR elements) provided in the magnetic head. The other ends of the conductors are connected to tail electrodes formed in the flexure tail. These tail electrodes are electrically connected to terminals of a circuit board such as a flexible printed circuit board (FPC). On the circuit board, a signal processing circuit such as a preamplifier is mounted.
A flexure tail disclosed in U.S. Pat. No. 8,325,446 comprises a tail pad portion comprising tail electrodes, and a test pad portion comprising test electrodes. The test pad portion is used for inspecting electrical characteristics of a magnetic head, and is cut off from a flexure tail after inspection has been carried out.
In the flexure tail having the test pad portion, when the test pad portion is cut off, a portion referred to as a stub which is left uncut is formed near the tail pad portion. A plurality of conductors which are left uncut are arranged in the stub. These conductors extend toward a cut surface of the stub from the tail electrodes, respectively. The tail electrodes are laid over terminals of a circuit board, and the tail electrodes and the terminals are electrically connected by bonding means such as ultrasonic bonding.
The conductors are covered by an electrically insulating cover layer. The conductors of the stub and conductors of the circuit board are electrically insulated from each other. Accordingly, even if the stub is laid over the conductors of the circuit board, it has been considered that this causes no problem in particular electrically. However, from the intensive study of the inventors of the present invention, it has been found that in a flexure tail having the stub as described above, a leakage current called crosstalk flows through read conductors when a pulse signal is passed to write conductors. The crosstalk becomes a cause of electrical characteristics of the disk drive to be adversely affected.